Why is "create snapshot (ghosts)" disabled? (baked sound F-Curves in Graph Editor)
The button you are after I believe is on the left of the ghost button.

Graph editor with 16 channels baked to sound to custom properties AA0 - AA15


Click on the cursor button (show_only_selected = False)  and it wont matter if the object you have baked the fcurves onto is selected or not.



Lastly I've added AA9 to the search field, and filtered to only show Speaker animations.  Now that is all this graph editor will display. If I used "AA1" as the filter string it would show AA1, AA10 ... AA15.  



The BGL overlay is from my Sound Drivers Addon and can be drawn on top of graph editor, 3D view and timeline.